1. Field of the Invention
The present invention relates generally to the lubricating and conditioning of textile fibers.
It relates particularly to a finish for acrylic fibers which affords efficient handling and processing thereof.
2. Prior Art
Finishes are universally applied to fiber surfaces to improve the subsequent handling and processing of the fibers. The composition and amount of finish applied depend in large measure upon the nature -- i.e., the chemical composition -- of the fiber, the particular stage in the processing of the fiber, and the end use in view.
For example, compositions denominated "spin finishes" are applied to acrylic fiber tows usually after stretching thereof and frequently prior to subsequent processing thereof including crimping, drying, cutting into staple lengths, carding, drawing, roving, and spinning. Such finishes provide lubrication, prevent static build-up, and afford a slight cohesion between adjacent fibers.
The application of such finishes is generally accomplished by contacting an acrylic fiber tow or yarn with a solution or an emulsion comprising at least one lubricant with antistatic properties. Wetting agents, as well as emulsifiers are also commonly found in such finish mixtures. Finish can also be applied to tow, yarn, or cut staple by spraying.
Acceptable finishes must fulfill a number of requirements in addition to providing a desired lubricating and antistatic effects. For example, they should be easy to apply (and to remove if desired), they should have good thermal and chemical stability, they should not adversely affect the physical or chemical properties of the fibers to which they are applied, and they should aid the subsequent processes to which the treated fibers are subjected.
Of the many compositions which have been proposed as fiber finishes, including finishes for acrylic fibers, some of the more noteworthy are found in the following: U.S. Pat. Nos. 3,306,850; 3,341,451; 3,341,452; 3,357,919; 3,421,935; 3,549,530 and 3,888,775; British Patent No. 1,053,403; as well as U.S. Pat. No. 3,894,314. Notwithstanding the efficacy of these and many similar compositions, finishes are often found wanting in certain important aspects, viz., their employment ordinarily results in one or a combination of the following undesirable conditions: (a) physical properties unacceptable for satisfactory fiber processing under a wide range of conditions; (b) heavy dust and card fallout; (c) substantial deposits on rolls and metal parts of drawing, roving, and spinning, equipment, and (d) non-uniformity in the drawing of the sliver, as evidenced by the presence of thick and thin regions therein which are subsequently found in yarn spun therefrom.